What is the likelihood of oculomotor (third cranial nerve) nerve decompression with endovascular treatment of a posterior communicating artery (PCoA) aneurysm?

From the Guidelines

Endovascular treatment of a posterior communicating artery (PCoA) aneurysm has a high likelihood of relieving oculomotor nerve compression symptoms, with the best results occurring when treatment is performed early and complete aneurysm occlusion is achieved. The likelihood of oculomotor nerve decompression with endovascular treatment of a PCoA aneurysm is supported by studies that show endovascular coiling results in substantially better patient outcomes than neurosurgical clipping, with a relative risk reduction of 22.6% and an absolute risk reduction of 6.9% for death or disability at 1 year 1.

Key Considerations

• The International Subarachnoid Aneurysm Trial (ISAT) showed that endovascular coil occlusion of cerebral aneurysms results in better patient outcomes than neurosurgical clipping, with a lower rate of seizures and rebleeding rates that were not considered significant 1.
• The Cerebral Aneurysm Rerupture After Treatment (CARAT) study found that the rerupture risk for coiled aneurysms was 0.11%, whereas it was 0% for clipped aneurysms, suggesting that endovascular coiling is a safe and effective treatment option 1.
• Factors that positively influence recovery from oculomotor nerve compression include shorter duration of symptoms before treatment, younger patient age, smaller aneurysm size, and absence of other vascular risk factors.

Treatment Recommendations

• Endovascular coiling or flow diversion techniques can effectively secure the aneurysm while allowing the compressed third cranial nerve to recover.
• Complete aneurysm occlusion is crucial for symptom resolution, as residual filling may maintain pressure on the nerve.
• Close follow-up with neuro-ophthalmologic evaluation is essential to monitor recovery progress after endovascular treatment.
• Patients should be managed in centers that offer both open surgical and endovascular techniques to ensure the best possible outcomes.

From the Research

Oculomotor Nerve Decompression with Endovascular Treatment

The likelihood of oculomotor (third cranial nerve) nerve decompression with endovascular treatment of a posterior communicating artery (PCoA) aneurysm can be assessed based on several studies.

• The recovery rate from oculomotor nerve palsy (ONP) after endovascular coiling was reported to be around 65-85% in different studies 2, 3, 4.
• A study published in 2014 found that 13 out of 14 patients treated with endovascular coiling initially recovered, but long-term follow-up revealed three cases of exacerbation of ONP after refilling of the aneurysms 2.
• Another study published in 2020 found that the recovery rate was 94.6% in the surgical clipping group and 65.0% in the endovascular coiling group, with a significant difference between the two groups (P < .001) 3.
• A review of 20 patients treated by endovascular coiling for PCOMM aneurysm-induced ONP found that all patients achieved oculomotor nerve recovery, with 9 (45%) patients having complete recovery and 11 (55%) patients having partial recovery 4.
• A retrospective comparison of surgical clipping and endovascular embolization found that significant differences were found in postoperative recovery time and recovery rates, with surgical clipping resulting in a higher recovery rate (98.5% vs 68.2%) 5.
• A systematic review and single-center series found that surgical treatment was associated with a significantly higher rate of complete ONP resolution (55% vs 32%) and ONP resolution of any degree (92% vs 74%) compared with endovascularly treated patients 6.

Factors Influencing Recovery

Several factors can influence the recovery of ONP after endovascular treatment, including:

• Time from ONP onset to treatment: A study found that the period between ONP onset and admission was associated with recovery 5.
• Presence of subarachnoid hemorrhage (SAH): A study found that ONP recovery in patients with SAH before surgery was also independently associated with ONP prognosis 3.
• Size and location of the PCOMM aneurysm: A study found that the size and location of the aneurysm may affect the recovery of ONP 4.